Pocket filter for air and gas purification

ABSTRACT

A pocket filter of V-shaped cross-section has, to define the pocket opening, two end plates and two side members, each of the side members having outwardly bent outer edges as a connecting piece for assembly with adjacent pocket filters; V-shaped clamps fit within the pockets to hold a strip of filter material in place.

1 1 Sept. 19, 1972 United States Patent Neumann [54] POCKET FILTER FORAIR AND GAS PURIFICATION [72] Inventor:

Nutting....................... 2,857,017 Nuttmg 2,966,959 1/1961Neumann................... 3,026,967

3/1962 Stevensetal................55/500 [73] Assignee:Delbag-Luitfilter Gesellschaft mit .55/500 FOREIGN PATENTS ORAPPLICATIONS Avera.......................

3,412,531 Schwab..,...................

beschrankter Haftung, Berlin, Germany 803,227 10/1958 GreatBritain...............55/496 [22] Filed: Feb. 2, 1970 PrimaryExaminerBernard Nozick Attorney-Karl F. Ross eFq n ypl cafiqn iqr txPataH- V Feb.26, 1969 Germany.. 69 08 374 55 484 755 SOD-GEMS; ABSTRACT I ll A pocket filter of V-shaped cross-section has, to

define the pocket opening, two end plates and two side members, each ofthe side members having out wardly bent outer edges as a connectingpiece for assembly with adjacent pocket filters; V-shaped clamps 12 l M%5x54 5 a v 5 03% ,M09 9 54 O B74 a fit within the pockets to hold astrip of filter material in place.

[56] References Cited UNITED STATES PATENTS I 13 Claims, 8 DrawingFigures 1 1913 Williamson................,.55/48 4 ill-III'IIIIIIII 11111 i.l l

)IIIII'IIIIIIIQ PATENTEDSEP 19 1912 3.691.736

sum 1 OF 5 iiiiiiiiiiiiiii'i'i y' GERHARD MAX NEUHANN lnren/on- Y my, KM

ATTORNEY PATENTEDSEP 19 4912 3.691.736

GLRl-LARD MAX lIQUi'LALJZC PATENTEDSEP 19 I972 3.691. 736

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lnrenfon- POCKET FILTER FOR AIR AND GAS PURIFICATION My presentinvention relates to a pocket filter for air and gas purification.

A known pocket filter utilizes large-surface-area multiple sack pocketsarranged in a reception housing of suitable shape. The manufacture ofthese sack pockets, which one also closed at the sides, and the joiningof several sack pockets by sewing or glueing the outer edges to adjacentpockets is very expensive and accordingly uneconomical, since theair-filter sacks are mostly throw-away articles.

To some extent there has come into use, for pocket filters of this type,a dry filter material in strip form. In these devices, zig-zag wiregrids are welded between upright sheet walls to receive a V-shape stripmaterial, consisting of glass wool, cotton wool or textile thread, heldin place by resilient removable frames. With these pocket filters thereis the disadvantage that the filter material cannot be satisfactorilysealed against the sheet wall since, on welding in the zig-zag wiregrid, the sheet walls are subject to deformation. If several pocketfilters of this type arranged one above or alongside the other to formbuilt-in filter walls satisfactory sealing between individual, uprightadjacent sheets of the housing is not obtainable at a high rate of dustremoval. These known filters are accordingly usable only for coarsefiltering; however, the cost of equipment in relation to the degree ofdust removal is very high.

Other known pocket filters comprise individual housings in which lateralsheets, i.e. end plates, bracket V-shaped, grid-like support memberswherein the stripshaped filter medium is placed. Clamp frames which maybe hingedly spread apart are provided for holding the filter material,these clamp frames being inserted in the plug-in opening of the housing.In this known construction the housings have a surrounding rim at theair-inlet side. When a number of individual housings are assembled toform a built-in unit, again the problem arises of reliable sealingagainst outside air, as regards both the individual housings in relationto each other and the filter medium in relation to the housing. Thesealing necessary for fine filtering is very expensive and absolutelysatisfactory seals can be obtained only at a great outlay of materialand work. Accordingly, these known pocket filters also are used mainlyfor coarse filtering unless additional sealing measures are carried out.

The present invention has for its object to provide a pocket filterwhich affords a good seal between the individual housings and betweenthe filter medium and the individual housings. It should be suitable forselective installation in filter ducting or in brickwork openings.

According to one aspect of the invention, I provide a plurality ofjuxtaposed filtering units each comprising at least one housing with twoend plates, a support grid of generally V-shaped cross-section bracketedby the two end plates to define a pair of apertured, rearwardlyconverging walls of a cell or pocket, and two parallel side members alsoextending between the end plates to define a pair of longitudinal edgesfor the rectangular insertion end of the pocket; each side member has anouter edge bent forward to constitute a connecting member or rib forattachment to a similar adjacent housing.

Usually,

bent edge portions to which the support grid is secured.

At least one end plate, and preferably both, may be bent back'out of itsplane at right angles to provide a cross-wall coplanar with theadjoining side members defining therewith a rectangular peripheralflange which frames the insertion end of the pocket.

A preferred special configuration of side member, designed to provideboth easy interconnection between housings and good sealing within thehousing, is a strip bent along three longitudinal fold lines, i.e. (a)orthogonally forwardly at a first line near one edge of the insertionend to define the connecting rib; (b) backwardly along a second,intermediate, line through 360 to form a doubled-over portion; and (c)outwardly through less than along a third line from the back of thisdoubled-over portion so as to extend backwardly, at an acute angle tothat portion the inwardly projecting doubled-over portion constitutes ashoulder for I retaining an internal filter clamp within the housing,

whereas the backwardly extending portion forms a' sealing strip to whichthe support grid is connected. Of course, this backwardly extendingportion will conveniently be so oriented as to be in line with the armsof the V-shaped grid defining the apertured walls of the housing.

Usually each side member extends beyond the end plate, by a distancecorresponding to the height of the cross-wall, and is recessed beyondthe end plate by removing the doubled-over portion to accommodate thecross-wall, the side members and cross-wall being joined together bywelding to form the peripheral flange.

For ease in fabrication the edges of the support grid may be bent overtoform hookl-like flanges, or cuffs complementary cuffs being providedon the side members and/or the end plates to fasten the support grid.

Such cuffs'may of course be located on the end of the backwardlyextending portion of the side member, and/or on the bottom of theinwardly bent portions of the end plate.

If desired, the side of members may span two or more like housings of afiltering unit separated by internal partitions which will not normallypossess bent-cover edges and which can be lodged face-to-face in slitsof suitable thickness in these side members. When the side member hasthe preferred folded-strip configuration referred to above, the slitsmay correspond in depth to the width of the remaining doubled-overportion.

According to a further aspect of the invention, the clamp consists oftwo similar, generally planar wire frames interconnected at the freeedges of the V by a spring member and at the apex of the V by welding orhinging.

To facilitate insertion and removal of the clamp, its free edges, onlyhave projections extending from the filter pocket.

The spring may be a leaf spring; by using a generally inwardly convexleaf spring provided with outwardly projecting bent portions, which canbe manually compressed to facilitate insertion and removal of the clamp,it is possible to dispense with projections on the frame for thispurpose. The same advantage applies to the use of a generally outwardlyconvex wound wire spring, whose limbs can be pressed inward manually.

each end plate is of a V-shape conforming to I the cross-section of thesupport grid and has inwardly According a further important aspect ofthe invention I provide a mounting unit wherein a plurality of filterunit as described above lie side-by-side with their connecting membersjoined together. Such a frame may have a rectangular central aperture,surrounded by an internally projecting web, in which the housings can bemounted and fixedly attached by their peripheral flanges to the web.

Such mounting-units are preferably assembled first by welding togetherthe individual housings and subsequently by welting the resultingassembly to the mounting frame; in each instance the welding is bestcarried out as step-spot weldingusing point welding paste.

A filter assembly according to my invention may consist of two or moreof such mounting units of generally rectangular shape mountedside-by-side.

'r A mounting unit can be disposed in an air duct and be provided with asealing member (endless rubber tube, or plastic caulking compound) inthe peripheral groove; additional sealing devices can be provided ifnecessary.

The accompanying drawing shows embodiments of the invention by way ofexample. In the drawing:

FIG. 1 is a perspective exploded representation of a mounting unitaccording to my invention;

FIG. 2 is an illustrationsimilar to FIG. 1 showing the filter materialand an associated clamp;

FIG. 3 is a fragmentary perspective of two individual housings joinedtogether;

FIGS. 4 to 6 are cross-sections of joined housings with differentlyconstructed spring members;

FIG. 7 is a fragmentary perspective view of a modified embodiment of amounting unit; and

FIG. 8 is a similar view of two mounting units set in a masonry opening.

The Figures show a housing assembly 1 carried in a mountingframe 3 andconstituting with it a mounting unit, the assembly 1 consisting of sevenindividual housings 2 arranged alongside. Each individual housing 2 hasa support member 4 formed of a wire grid. FIG. 2 shows a filter mat orstrip ,5, bent in a V-shape, which is inserted in the individual housing2 and held by a clamp 6. As can be seen in particular from FIGS. 1, 3and 4 to 6, the individual housing 2 consists of an upper and a lowerend'plate 7 between which the support grid 4 is mounted. The insertionopening of the housing 2 is surrounded by a peripheral flange 8including two longitudinal side members 9 which have upright forwardlybent portions or ribs 10. The ribs 10 of two adjacent side members 9 aresealingly interconnected by steppoint welding. As FIGS. 4-6 show, theside member 9 has a blocking strip or abutment means formed by a fold ordoubled-over portion 1], projection into the insertion opening, joinedto an inwardly bent resilient sealing strip 12 to which the support grid4 is attached. An outwardly bent transverse edge of each end plate 7forms a cross-wall l3 constituting one of the minor sides of therectangular peripheral flange 8. On assembly of the individual housingfrom the side members and end plates, the cross-walls 13 are placed incomplementary cutouts 14 of the longitudinal side members coplanartherewith, the depth of each cutout being equal to the width of thefolded strip portion 11. A continuous housing edge is formed by thecompleted flange 8 upon welding the cross-walls 13 to the side members9.

Cuffs flanging 15 are provided on the edge of the sealing strip 12 forreceiving the support grid 4. The free edges of the end plates 7haveorthogonally bent back portions 16, which are also provided withcuffs 17. As FIG. 1 shows, the support grids 4 have complementaryinwardly directed cuffs 18 at their free edges. For fixing the supportgrid 4 to the housing, the cuffs 18 of the support grid 4 are engagedwith the cuffs l5, l7 and secured thereto by a flanging tool. Of course,the support grids 4 may for instance also be connected to the individualhousing 2 by spot welding or in some other manner.

A mounting frame 3 has a peripheral edge 19 and an inwardly projectingweb 20 which forms an opening 21 corresponding to the totalcross-section of the housing assembly 1. As FIGS. 1 and 2 show, themounting frame 3 is pushed from the rear over the assembly lso that thecross-walls 13 come to rest on the web 20. They are then connected tothe web by step point welding. The same thing takes place with theoutermost side members 9 of the assembly 1 so that an assembly l isobtained which is sealed off completely against air leakage and seatedin the mounting frame 3.

As FIG. 2 shows, a mat of filter material 5, folded in a V-shape, isplaced in each individual housing followed form a pair of rear legs 24integral with transverse legs 25 and front legs 26. Projections 27,through which the two individual frames 22 are welded or held togetherby eyes not shown, are offset from the legs 24. Between the legs 26lies'a resilient spring member 28. To insert the clamp 6, the free frontlegs 26 are pressed together and the clamp 6 is thrust into the openingof the housing. As FIGS. 4 to 6 show, when this takes place the legs 26of the clamp 6 press outwardly against the sealing strip 12 of thehousing. Simultaneously the blocking strips 11 prevent the clamp 6 fromundergoing any unintended change of position, so that satisfactorysealing of the filter mat 5 into the individual housing 2 is maintained.

FIG. 5 shows a spring member in the form of an inwardly curved leafspring 28 which has eye-like outwardly projecting bent-back portions 29,its ends being fixed to the clamp legs 26.

FIG. 4 shows a modified embodiment, in which legs 26 of clamp 6 are bentoutwardly at 30 to facilitate compression of the clamp frame and whereinthe spring member is an outwardly curved leaf spring 31 fastened to thelegs 26. FIG. 6 shows a further modification in which an outwardlycurved wire spring 32, having two turns and leg portions 33 which can begripped for the compression of the clamp 6, is fixed to the legs 26 asthe resilient clamp spreader.

The periphery 19 of the mounting frame 3 has a peripheral stiffeninggroove 34 in which, as FIG. 8 shows, a seal 35 is placed when two ormore mounting frames 3 are connected to one another by screws passingthrough bores 36.

FIG. 7 shows a modified embodiment in which there are continuous sidemembers 37 extending over the height of several individual housings 2forming part of a plurality of juxtaposed filtering units. The outermostend plates 7 of the stack of individual housings 2 are each equipped inthe aforedescribed way with the cross-wall 13, but the intermediatepartitions 39 parallel to and coextensive with these end plates do notpos- 5 sess such cross-walls 13. Members 37 have notches 38 extendingover the width of the doubled-over blocking strip 11 and having a depthamounting to double the wall thickness of the end plates 39 which cantherefore be held in pairs in the notches 38, and welded and sealed toeach other and (at the notches 38) to the longitudinal side members 37.When this assembly is mounted in the frame 3, it is necessary to weldthe outermost side members 37 and the outermost cross-walls 13 to theweb 20.

When an assembly 1 according to the invention, carried in the mountingframe 3, is to be mounted in a duct housing, a surrounding sealing lipis provided at the front edge of the rim 19 of the frame 3.

l claim: 1 20 l. A filter comprising:

a plurality of juxtaposed filtering units each including at least onehousing with an insertion opening framed by a rectangular planar flange,two parallel end plates extending rearwardly from the minor sides of therectangular flange and terminating in the plane of the flange in twooutwardly bent edges defining said minor sides, and a pair of aperturedsidewalls extending rearwardly from the major sides of the rectangularflange to define a unitary grid in engagement with said end plates, themajor sides of said rectangular flange being defined by a pair ofparallel strips coplanar with said outwardly bent edges, said stripsbeing orthogonally bent forwardly from said major sides beyond saidsidewalls to form a pair of ribs transverse to said end plates, saidribs being bonded in fluidtight manner to corresponding neighboring ribsof adjacent housings;

a sheet of filter material in each housing overlying said sidewallsthereof;

clamping means in each housing removably retaining said sheet of filtermaterial therein in contact with said sidewalls, said strips havingportions projecting inwardly past said sidewalls to form a pair of 45shoulders holding said clamping means in position within each housing;and

a mounting frame embracing said housings in fluidtight contact with atleast said outwardly bent edges of said rectangular flange of eachhousing, the sidewalls of adjacent housings being spaced apart to definea fluid passage. I

2. A filter assembly as defined in claim 1 wherein said mounting frameis provided with, peripherally spaced holes for fastening same to asubstantially identical mounting frame of an adjoining assembly.

3. A filter assembly as defined in claim 1 wherein said strips extendbeyond said perpendicular planes whereas said inwardly projectingportions thereof terminate at said planes, thereby forming cutoutsaccommodating respective corners of said end plates together with partsof said outwardly bent edges complementary to said cutouts.

4. A filter assembly as defined in claim 1 wherein said mounting framehas an inner peripheral web of rectangular configuration abutting saidoutwardly bent edges in bonded relationshig therewith.

. A filter assembly as efined in claim 1 wherein said strips are foldedback upon themselves along said projecting portions and are thenceextended rearwardly in line with said sidewalls and in positiveengagement therewith.

6. A filter assembly as defined in claim 5 wherein said strips areprovided at their rear edges with cuffs hooking onto complementary cuffson said sidewalls.

7. A filter assembly as' defined in claim 1 wherein each of said unitscomprises a plurality of stacked housings bracketed by said end plates,said strips being common to all the housings of a unit.

8. A filter assembly as defined in claim 7 wherein said stacked housingsare separated by partitions parallel to said end plates andsubstantially coextensive therewith.

9. A filter assembly as defined in claim 8 wherein said strips areprovided with slits in said inwardly projecting portions receiving saidpartitions.

10. A filter assembly as defined in claim 9 wherein said partitions areduplicated on adjoining housings of a unit and are jointly inserted intosaid slits.

11. A filter assembly as defined in claim 1 whereiri said clamping meanscomprises a wire structure with separable halves and resilient meansurging said halves apart toward said sidewalls.

12. A filter assembly as defined in claim 11 wherein said halves havefront legs located behind said shoulders, said resilient means beinglooped forwardly between said shoulders for manipulation to extract saidstructure from the housing.

13. A filter assembly as defined in claim 12 wherein said front legs areprovided with gripping formations extending forwardly between saidshoulders.

1. A filter comprising: a plurality of juxtaposed filtering units eachincluding at least one housing with an insertion opening framed by arectangular planar flange, two parallel end plates extending rearwardlyfrom the minor sides of the rectangular flange and terminating in theplane of the flange in two outwardly bent edges defining said minorsides, and a pair of apertured sidewalls extending rearwardly from themajor sides of the rectangular flange to define a unitary grid inengAgement with said end plates, the major sides of said rectangularflange being defined by a pair of parallel strips coplanar with saidoutwardly bent edges, said strips being orthogonally bent forwardly fromsaid major sides beyond said sidewalls to form a pair of ribs transverseto said end plates, said ribs being bonded in fluidtight manner tocorresponding neighboring ribs of adjacent housings; a sheet of filtermaterial in each housing overlying said sidewalls thereof; clampingmeans in each housing removably retaining said sheet of filter materialtherein in contact with said sidewalls, said strips having portionsprojecting inwardly past said sidewalls to form a pair of shouldersholding said clamping means in position within each housing; and amounting frame embracing said housings in fluidtight contact with atleast said outwardly bent edges of said rectangular flange of eachhousing, the sidewalls of adjacent housings being spaced apart to definea fluid passage.
 2. A filter assembly as defined in claim 1 wherein saidmounting frame is provided with peripherally spaced holes for fasteningsame to a substantially identical mounting frame of an adjoiningassembly.
 3. A filter assembly as defined in claim 1 wherein said stripsextend beyond said perpendicular planes whereas said inwardly projectingportions thereof terminate at said planes, thereby forming cutoutsaccommodating respective corners of said end plates together with partsof said outwardly bent edges complementary to said cutouts.
 4. A filterassembly as defined in claim 1 wherein said mounting frame has an innerperipheral web of rectangular configuration abutting said outwardly bentedges in bonded relationship therewith.
 5. A filter assembly as definedin claim 1 wherein said strips are folded back upon themselves alongsaid projecting portions and are thence extended rearwardly in line withsaid sidewalls and in positive engagement therewith.
 6. A filterassembly as defined in claim 5 wherein said strips are provided at theirrear edges with cuffs hooking onto complementary cuffs on saidsidewalls.
 7. A filter assembly as defined in claim 1 wherein each ofsaid units comprises a plurality of stacked housings bracketed by saidend plates, said strips being common to all the housings of a unit.
 8. Afilter assembly as defined in claim 7 wherein said stacked housings areseparated by partitions parallel to said end plates and substantiallycoextensive therewith.
 9. A filter assembly as defined in claim 8wherein said strips are provided with slits in said inwardly projectingportions receiving said partitions.
 10. A filter assembly as defined inclaim 9 wherein said partitions are duplicated on adjoining housings ofa unit and are jointly inserted into said slits.
 11. A filter assemblyas defined in claim 1 wherein said clamping means comprises a wirestructure with separable halves and resilient means urging said halvesapart toward said sidewalls.
 12. A filter assembly as defined in claim11 wherein said halves have front legs located behind said shoulders,said resilient means being looped forwardly between said shoulders formanipulation to extract said structure from the housing.
 13. A filterassembly as defined in claim 12 wherein said front legs are providedwith gripping formations extending forwardly between said shoulders.